Crime novelist Ariadne Oliver again turns to Hercule Poirot, this time to solve a case the police consider closed. Olivers interest in the murder-suicide of General and Lady Ravenscroft is more than academic: Celia Ravenscroft is her goddaughter. This is one of Poirot's most daunting cases  even he begins to doubt he can solve it  since the investigation relies on memories from years earlier.